The present invention relates to a ridge vent for roofs, and in particular to a ridge vent for use on asphalt shingle or other composition roofs, preferably having a pitch of at least 2/12.
It has been known to ventilate attics under gable roofs by running a vent along the roof ridge. Such vents are created during construction by sizing the uppermost row of sheathing panels to leave an open slot running along the ridge essentially the length of the roof. The slot creates effective heat ventilation by convection flow and suction caused by wind across the roof ridge.
Soffit ventilators are perforated or louvered openings located along the eaves of an overhanging roof. The vents allow fresh ambient air to flow into the attic to equalize attic temperature and pressure with the outside. This equalization inhibits moisture from condensing on insulation and wood roofing materials which causes mildew and rot, prevents build-up of ice dams which could buckle shingles and gutters, and reduces air-conditioning costs when hot attic air is replaced by cooler ambient air.
A soffit ventilation system works in conjunction with a ridge vent to provide passive ventilation. As hot stale air is withdrawn from the ridge slot vent by convection and/or wind suction, it is replaced by fresh ambient air through the soffit vents.
One known ridge vent that has proven to be very successful is described in the inventor's prior U.S. Pat. No. 5,167,579. This roof vent is formed using a non-woven synthetic fiber mat having randomly aligned fibers located over a vent slot at the roof ridge. Cap shingles are then installed over the non-woven synthetic fiber mat. The synthetic fiber mat allows for air flow through the slot at the roof ridge, while preventing the ingress of moisture and debris. However, while this type of vent has proven effective at stopping the ingress of most moisture coming up the roof slope, for example due to wind driven rain, it cannot prevent moisture ingress from above, such as when wind driven rain is oriented parallel to the roof ridge line, forcing water between the cap shingles, where it then can pass directly down through the vent material.
Other known systems utilize an open-celled foam material with an upper membrane of closed cell that covers the ridge vent slot. However, this comes in short lengths that must be pieced together. Additionally, the foam materials can retain moisture in the cells due to the meniscus forces of the water in the open cells, reducing the effective ventilation area.
Depending on the installation techniques used, generally all of the prior known systems can allow leakage due to wind driven rain.
It would therefore be desirable to provide a roof ridge vent system that allows for easy and consistent installation by roofing installers and which provides effective ridge ventilation while preventing moisture ingress.